Weld strength testing apparatus



July 4., 1944. F. MARTINDELL WELD STRENGTH 'IEES'JJINfr` APPARATUS FiledMarch 26, 1942 Patented Julyv4, 12244 lf f UNlrso srArss PAT n WELDSTRENGTH TESTING APPARATUS Frank Martlndell, Western Springs, Ill.,assigner to Western Electric Company, Incorporated, New York, N. Y., acorporation of New York Application March 2s, 1942, serial No. 436,306

2 claims. (c1. 265-14) vrI'his invention relates to weld strengthtesting apparatus and more particularly to a recording testing apparatusfor testing the quality of welding of electrical contacts lto contactsprings.

In the manufacture of electrical switching ap,-n paratus, such as relaysand other types o! switches, particularly those used in the telephoneindustry, the process ci4 attaching precious metal contacts to contactsprings by welding has been almost universally adopted. Since it isessential that these contacts have a long life oi service,

various devices have been provided for testing to destruction a smallpercentage of welds connecting the precious metal contacts to thecontact springs in order to determine the quality of the welded jointbetween the contact and the spring which supports it. In following thispractice, an operator of a welding machine may select, for example, oneor two contacts out oi eachV 100 or 200 contacts which have been weldedto contact springs and measure the amount of Venergyit requires to stripthe precious metal contact from.

the spring. By thus destroying the welded con` nection between one ortwo contacts out of G or 200 contacts, the operator is able to determinenected with the cylinder to record the pressure a applied to the pistonto sheary the contact from the shearing position, the air in backoii'zhe piawhether the welding device being used is func- .tioningproperly. Numerous devices have, inthe past, been devised for performingthis operation ;r for example,y the apparatus shown in the patent to J.S; Stull of November 4, 1941, No. 2,261,783, wherein a manually actuateddevice kfor testing welds to destruction is disclosed.

It is an object of the present invention to provide a simple andeilicient weld strength testing apparatus which will automaticallyrecord the amount ofienergyrequired to break a weld.

In accordance with one embodiment of the in'- vention, there isprovided'a pneumatically actuatedshearing mechanism for shearingprecious metal contacts lfrom contact springs and a recorder forautomatically recording the -amount of pressure applied to the contactto strip it irom the contact springs. In this apparatus, air underpressure is admitted through a manually controlled valve to an aircylinder in which there is positioned a piston normally held in aretracted position by a coiled spring. The air underA pressure willforcethe piston to carry a shearing member supported by it against a contacton a contact spring with sufficient force to shear the contact from thecontact spring, which is, in turn, held against movement by an anviliixed with respect to the cylinder. Any well-known type oi' pressurerecording device may be con-` the contact spring. In thehereinndescrihed eine bodiment of 'the inventicn`a cardboard disc,driven by suitable mechanism, is tr-vided which the record of thesuccessive Weide tested may be marked by the needle of a recordingpressure gage. The cylinder in the present emhodi ment of the inventionis provided with an vescape port so that when the contact is sheared thecontact spring and the piston moves beyo ton may escape through thisport and f: ties manner, the highest pressure attained. inthe cyl-.-inder will be recorded on the record disc and after the contact issheared from the contact spring, the pressure in the cylinder willimmediately fall due to theescape of the airV througm the escape port.The interior walls of the cylinder and exterior walls ci the piston areso proportioned that after a contact has been sheared from the contactspring, the piston maybe-re.- turned to its normal positicn by itsbiasing spring.

A better understanding ofthe invention may be had by reference to theallowing detailed description of one embodiment thereof when consideredlin conjunction with the accompanying drawing, wherein Fig. 1 is aperspective view o the pressure applying mechanism vand recordingmechanism constituting the Vpreferred .embodiment of this invention; iFig. 2 Vis a plan view of the mechanism for shearing a contact from acontact spring;

Y Fig., 3 is an en d elevational view of the structure shown in Fig. 1:and

Fig. 4 is a side elevational view of the structure shown in Figs. 2 and3, part being brokenV wherein a recording stylus .IS is moved through 1an arc proportional to the pressure of the air supplied to the recordingdevice through the hose I2 and wherein the stylus I3 cooperates with adisc type record lt to niark on the record it one line I each time atest is made in the weld shearing mechanism I I. The disc type record I4may be driven in any suitable manner; for example, by a clock mechanism(not shown) or may be stepped forward each time a testing operation isperformed, as is customary in recording devices of this type. It will benoted that the stylus I3, in marking the lines I5 on the record I4,starts at a point I6 and moves clockwise through varying distancesdepending upon the pressure within the pressure recording device I0.

The hose I2 is connected to a port 29 communieating with a passage 2I.The passage 2I has in communication with it a smaller passage 22 -whichcommunicates with the interior 25 oi a cylinder block 28. The interior25 of the cylinder block 26 is in communication with a passage 21, theinlet of which receives the tapered end oi' a threaded member 23,provided with a knurled head 24. The threaded member 23 may be rotatedto adjust the eilective opening from a passage 28 into the passage 21,thereby to regulate the flow of air under pressure into the cylinder 26.An inlet port 28 is in communication with a passage 28. The inlet port29 has a hose 80 connected thereto and toa source of air under pressure.'I'here is provided in the hose 3|! a manually operable valve 3 I,having an actuator plunger 22, which, upon operation, will permit airunder pressure to ilow through the hose 38 and passages 28 and 21 to theinterior 25 of the cylinder block 28.

Positioned in the cylinder block 26 is a piston 36, having threaded intoits right hand end (Fig. 4) a shouldered plug 31, having extendingupwardly from it a shearing member 38 for cooperation with anvils 39--38to shear a contact 40, as shown in dot and dash lines (Fig. 4) from acontact spring 4I, also shown in dot and dash lines (Fig. 4).

The piston 36 is hollow and is normally urged to the left (Fig. 4) by acompression spring 42. compressed between the inside oi the piston headand a washer 43, seated against a shoulder 44 of a threaded member 45.The threaded member 45 is threaded in a transversely extending portionof an end block 41, suitably fixed to the cylinder block 28. The anvils39 are carried on plates 50 and 5I secured to the cylinder block 28 andpositioned between a shoulder 52 formed on the cylinder block 26 and theend block 41. The cylinder block 26 is provided with an aperture orescape port 53 leading into the interior 25 of the cylinder block 26 butnormally sealed from communication with the interior by the piston 36.

In the operation of the apparatus, a contact spring 4I having a contact4U thereon, may be positioned with the end of the spring 4I abutting theanvils 39 and with the contact 40 in the path of the shearing member 38.Thus, valve 3I may be operated to admit air under pressure to theinterior 25 of cylinder block 26. When air under pressure is admitted tothe interior 25 of the cylinder, through hose 30, inlet port 29 andpassages 28 -and 21 by an operator actuating the plunger 32, the piston36 will move to the right, to apply a shearing force, tending to shearcontact 40 from contact spring 4I. As the pressure in the interior ofthe cylinder 25 builds up, the pressure recording device, being incommunication with the interior of the cylinder, will record thepressure and the stylus I3 will rock clockwise to inscribe a mark on therecord disc I4. The length of the line I5 inscribed by the stylus on therecord disc I4 will be proportional to the pressure within the cylinder2l and the stylus I3 will continue to move clockwise so long as thepressure continues to increase within the cylinder 2l. As soon as thecontact 4l is sheared from the spring 4I, the piston 35 will moverapidly to the right (Fig. 4) to move its left edge beyond the apertureorl escape port 5l and thus if the iiow of air intothe interior 25 ofthe cylinder 26 is maintained by the operator holding the plunger 22down, no appreciable pressure will build up within the cylinder due tothe escape of the air through the aperture 53 and thus no falserecordings will be made by the recording device I6.

The interior of the cylinder 25 and the exterior of the piston 58 are soproportioned that the spring 42 may force the piston 86 back to theposition shown when no air under pressure is being delivered to theinterior 25 oi the cylinder and thus the apparatus will restore itselfto normal as soon as the operator releases the actuator plunger 32.

What is claimed is:

1. A weld strength testing and recording apparatus comprising a pressureresponsive recorder, a cylinder in communication with said recorder,means on said cylinder for holding one of a pair of welded-togetherarticles against movement, a piston in said cylinder having meansthereon for engaging the other of said pair of welded-together articles,resilient means for normally maintaining the piston in a predeterminedpositionI means for supplying air under pressure to lsaid cylinder toimpart movement to the piston against the resilient Ameans for shearingthe welded-together members one from the other, and an escape port insaid cylindernormally blocked by the piston and positioned to permit theair admitted under pressure thereto to escape directly from the cylindersolely by movement of the piston out of blocking association therewithafter one of the articles has been stripped from the other article.

2. In an apparatus for testing welded joints and recording said tests,means for rigidly supporting an article to which a second article isattached by a welded joint, a cylinder, a piston in said cylinder havingmeans thereon for engaging the second-mentioned article, means formaintaining said piston in a predetermined position within the cylinder,means for supplying air under pressure to said cylinder and actingagainst the action of said maintaining means, a recording device inconnection with said cylinder for recording the pressures in saidcylinder, and an escape port formed in the side wall of the cylinderadjacent the end of the piston and normally closed by the side of thepiston, said port `being uncovered by movement of the `piston to permitair to escape directly from said cylinder when one of said articles hasbeen sheared from the other, the escape port being positioned tocommunicate directly with the interior of the cylinder beyond'the end ofthe piston when the piston moves.

FRANK MARTINDELL.

